there are a few points to clear up on this topic.
1. Minneapolis is one of the world hubs for KLM and Northwest, there are 2, 3 daily in summer flights between amsterdam and msp. The AMS end feeds a lot of pax from KLM uk flights, therefore, in theory, the UK-MSP market, along with NWs own LGW service is amply covered. Do not underestimate reluctance to switch carriers, for example, if a passenger in Bristol, Teesside or Humberside wanted to get to MSP, would they take the arduous road journey to LGW to connect with expensive BA, or would they take a hop accross to AMS and connect there, yes they would, and DO.
2. Detroit is also served by KLM, and in the high summer, there are 5 return dailies between DTW and AMS, op by KL/NW. Condor also fly there in the summer.
3. BAs Tampa service has a very high load factor, in my experience, those 300+ seats are always full, and it has puzzled me as to why the frequency has not been increased on the route.
4. All this talk of smaller markets, they are not served by BA, because, they can only really support one transatlantic service a day, if that. For example, BA dont fly to MEM, because of the daily KLM M11 to Ams, and because, without a tie-up with NW, there are very few connecting flights out of MEM. The same can be said for CLE, CO operate a daily LGW 752, summer only at the moment, and again, there is a lack of options for connecting pax out of CLE.
i appreciate that the population of MSP is large, and personally, i believe that a daily BA 763 could be a success, BUT, sep 11th has had a severe impact on travel between the states and europe, and i think it will be quite some time before the market gets back into its growth spurt.